The present invention pertains to a device for the rotative scoring of flat printed products.
In the scoring of folded sections, brochure covers, dust jackets, or similar printed products (herein, “printed book products”), the paper material, cardboard material or pasteboard material is deformed into a straight bead or the like by means of compression and/or displacement such that a hinge-like bending line is formed in the sheet. In adhesive binders and folding machines, the scoring is frequently carried out in a rotative fashion, wherein one or more scoring knives and assigned scoring matrices are arranged on parallel scoring shafts that are driven in opposite directions. In order to transport and guide the sheets, transport rollers are arranged on the scoring shafts adjacent to the scoring tools and effectively clamp the sheet with respect to its transport [Prospectus Kolbus KM 473: Kolbus Perfect Binding 8000 cycles/h; April 2004; Kolbus GmbH & Co. KG, D-32369 Rahden].
Due to the common arrangement on the scoring shafts, the scoring tools and the assigned transport rollers always have the same axial spacing. This creates an interrelationship that leads to a conflict in the adjustment of the scoring shaft spacing. On one hand, the adjustment of the spacing is used for varying the scoring intensity or scoring depth as the scoring knives penetrate more or less deep into the material. On the other hand, the adjustment of the scoring shaft spacing makes it possible to vary the clamping of the sheets by the transport rollers that are realized elastically on their working surface, wherein the sheet thickness also needs to be taken into consideration. This adjustment of the spacing is carried out in order to ensure a flawless and straight transport without markings by the transport rollers. The transport and the scoring influence one another. With respect to a deep scoring, the transport rollers are adjusted excessively narrow and mark, in particular, sensitive sheet surfaces. Bending and swinging of the scoring shafts may simultaneously occur such that the scoring quality also deteriorates.
In order to process brochure covers with cover flaps that are folded in on one side, both scoring shafts can be adjusted such that they are inclined relative to one another in order to thusly adjust the material thickness between the respective pairs of transport rollers that varies transverse to the scoring direction of the sheet. However, this results in fluctuations between the respective spacing of several pairs of scoring tools that are arranged adjacent to one another on the two scoring shafts such that the grooves produced twofold or fourfold in the spine region of the cover sheet have distinctly different depths.